Figure 6 A contrast enhanced magnetic resonance image of the left atrium (LA) showing a severe ostial stenosis of the left superior pulmonary vein. The body of the left atrium is viewed in the anteroposterior (AP) projection. The right superior and inferior pulmonary veins are visible and the arrow indicates the stenosis. This patient was asymptomatic; however, reduced perfusion to the left lung was demonstrated by a VQ scan and a successful balloon angioplasty of this vessel was performed.